Goal understands that despite continued public insistence from United manager David Moyes that Rooney is not for sale, officials from both clubs have held informal dialogue over a potential deal for the forward in the last 48 hours.

Central to those talks has been the disparity in the two clubs' valuation of the Rooney, with United are holding out for £40 million having instantly rejected Chelsea’s second bid for the 27-year-old, worth around £30m.

However, United have also used discussions to reiterate their interest in Mata, who was rumoured along with David Luiz to be offered to the Premier League champions as part of the Blues’ initial offer for Rooney.

Chelsea at the time denied including any of their own players in the deal while confirming that their written bid had been rejected.

But United's willingness to re-enter dialogue about a potential deal only 12 days before the transfer window closes will encourage the Blues in their hope of yet doing a deal for the England international.

"Wayne is acting and training professionally at Carrington but is making no secret of his desire to leave," a source close to United told Goal.

While the club and Moyes are not keen on selling him to a rival on the back of a frustrating summer transfer window, United feel compelled to explore all avenues should he submit a transfer request in an attempt to force a move.

They believe the arrival of Juan Mata - although unlikely - would certainly go a long way to appeasing fans should that happen.

Mata was left on the bench for Chelsea’s Premier League opener against Hull having missed much of the club’s pre-season preparations following the Confederations Cup.

Chelsea manager Jose Mourinho has insisted that Mata is part of his plans this season but their are doubts over how the attacking midfielder will fit in to the Portuguese’s system.

Mourinho is desperate to land a top class striker this summer having started the season with Fernando Torres, Romelu Lukaku and Demba Ba as his three forwards.

Chelsea failed with attempts to bring Radamel Falcao, Edinson Cavani and Robert Lewandowski to Stamford Bridge before turning their attention to Rooney.

Mourinho claimed in July that Rooney was his only target, but insisted this week that the Londoners have been making alternative plans.